Christopher Nolan's mind-bending, intelligent, exciting and disturbing sci-fi extravaganza, starring Leonardo DiCaprio, blends the best of traditional and modern filmmaking.

Dreaming is life's great solitary adventure. Whatever pleasures or terrors the dream state provides, we experience them alone or not at all.

But what if other people could literally invade our dreams, what if a technology existed that enabled interlopers to create and manipulate sleeping life with the goal of stealing our secret thoughts, or more unsettling still, implanting ideas in the deepest of subconscious states and making us believe they're our own?

Welcome to the world of "Inception," written and directed by the masterful Christopher Nolan, a tremendously exciting science-fiction thriller that's as disturbing as it sounds. This is a popular entertainment with a knockout punch so intense and unnerving it'll have you worrying if it's safe to close your eyes at night.

Having come up with the idea when he was 16, Nolan wrote the first draft of "Inception" eight years ago and in the interim his great success with "Batman Begins" and "The Dark Knight," not to mention the earlier "Memento," put him in a position to cast Leonardo DiCaprio and six other Oscar-nominated actors and spend a reported $160 million in a most daring way.

For "Inception" is not only about the dream state, it often plays on screen in a dreamlike way, which means that it has the gift of being easier to follow than to explain. Specifics of the plot can be difficult to pin down, especially at first, and guessing moment to moment what will be happening next, or even if the characters are in a dream or in reality, is not always possible. But even while literal understanding can remain tantilizingly out of reach, you always intuitively understand what is going on and why.

Helping in that understanding, and one of the film's most satisfying aspects, are its roots in old-fashioned genre entertainment, albeit genre amped up to warp speed. Besides its science-fiction theme, "Inception" also has strong film noir ties, easily recognizable elements like the femme fatale, doomed love and the protagonist's fateful decision to take on "one last job."

That would be DiCaprio's Dom Cobb, a thief who specializes in what's called extraction, in taking secrets from the subconscious. Aided by Arthur (a fine Joseph Gordon-Levitt), the trusted associate who is a whiz at the mechanics involved, Cobb is introduced in the middle of a dream involving Saito ( Ken Watanabe), a wealthy Japanese businessman.

That one last job is soon proposed by Saito, who asks Cobb if he is also able to do inception, the planting of ideas, a maneuver many people believe can't be done. Saito promises Cobb, who has a past which prevents him from returning to his children in America, the one thing he can't resist. If he takes on this one last job, if he agrees to practice inception on Robert Fischer ( Cillian Murphy), the heir to a multibillion-dollar energy empire, he will be able to return home.

In true movie fashion, Cobb has to round up a team to do the job. Aside from Arthur, he needs Eames, the forger (Tom Hardy), gifted at impersonating people inside dreams, and Yusuf, the chemist ( Dileep Rao), who makes the compounds that put people under. And with the aid of his father-in-law Miles ( Michael Caine), he meets Ariadne.

Named after the mythological character who helped Theseus find his way out of the Minotaur's labyrinth, Ariadne is a young architect who is needed to create the subconscious landscapes in which the dreams will take place. As played by Ellen Page, adroitly cast for her youth, intelligence and earnestness, Ariadne is the team's last essential element.

In addition to not knowing what they'll find inside Fischer's dream (believe me, there's plenty going on), Cobb and his team have to contend with a wild card: Mal, the untrustworthy femme fatale, a woman with deep and complicated ties to Cobb's past and someone who specializes in finding her way into dreams where she is not wanted.

The selection of Oscar-winning French actress Marion Cotillard as Mal typifies the care Nolan has taken to cast these thriller roles for emotional connection, a move which pays off in the scenes she shares with DiCaprio. In addition to the impeccably professional Batman veterans Caine and Murphy, the film is also on the money with the smaller roles, including Pete Postlethwaite as Fischer's ailing tycoon father and Tom Berenger as one of his key associates.

The reason all these diverse elements successfully come together is Nolan's meticulous grasp of the details necessary to achieve his bravura ambitions. A filmmaker so committed he does his own second unit direction, Nolan is one of the few people, to quote F. Scott Fitzgerald on film mogul Monroe Stahr in "The Last Tycoon," "able to keep the whole equation of pictures in their heads."